3-(Diphenylphosphino)propanoic acid: An efficient ligand for the Cu-catalyzed N-arylation of imidazoles and 1H-pyrazole with aryl halides

Article abstract of DOI:10.1016/j.cclet.2014.01.042

3-(Diphenylphosphino)propanoic acid (L2) has proved to be an efficient ligand for the copper-catalyzed CN coupling reactions. N-arylation of imidazoles with aryl iodides catalyzed by CuCl/L2 was smoothly carried out in DMSO at 100 °C with a yield up to 98%. N-arylation of 1H-pyrazole with aryl iodides and bromides catalyzed by Cu(OAc)₂/L2 in 1,4-dioxane also gave the corresponding products with yields of 40%-98%.

Full text of DOI:10.1016/j.cclet.2014.01.042

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CCLET-2869; No. of Pages 4
Chinese Chemical Letters xxx (2014) xxx–xxx
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Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Original article
3-(Diphenylphosphino)propanoic acid: An efficient ligand for the
Cu-catalyzed N-arylation of imidazoles and 1H-pyrazole with
aryl halides
Ya-Shuai Liu, Yan Liu, Xiao-Wei Ma, Ping Liu *, Jian-Wei Xie, Bin Dai
School of Chemistry and Chemical Engineering/Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi
8
32003, China
A R T I C L E I N F O
A B S T R A C T
Article history:
3-(Diphenylphosphino)propanoic acid (L2) has proved to be an efficient ligand for the copper-catalyzed
C–N coupling reactions. N-arylation of imidazoles with aryl iodides catalyzed by CuCl/L2 was smoothly
carried out in DMSO at 100 8C with a yield up to 98%. N-arylation of 1H-pyrazole with aryl iodides and
Received 27 November 2013
Received in revised form 31 December 2013
Accepted 16 January 2014
Available online xxx
bromides catalyzed by Cu(OAc)
0%–98%.
2
/L2 in 1,4-dioxane also gave the corresponding products with yields of
4
ß 2014 Ping Liu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Keywords:
Cu catalyzed
C–N coupling
N-arylation
P,O ligands
1
. Introduction
N-arylheterocycles represent an interesting structural motif
P,O-bidentate derivatives are well-known ligands for organic
reactions catalyzed by transition metals. The P,O chelating ligands
can provide additional coordination sites for the catalytic metal
center and, thus enhance their efficiency because they not only
supply suitable electrons, but also make available steric properties
to the phosphorus coordinating atom. Since Keim first reported
that nickel(II)/P,O chelating ligands were highly active in
oligomerization and polymerization of ethylene [19], this class
of ligands became the focal point and center of interest, and many
analogous ligands had been successively synthesized, especially
the ligands found in the development of novel homogeneous
catalysts [20]. In addition, a notable achievement had been made in
the utilization of P,O chelating ligands. The Pd- and Ni-catalyzed C–
C coupling reactions could be achieved under mild conditions [21–
23]. However, investigations on the Cu-catalyzed C–N coupling
reactions in the presence of P,O chelating ligands were seldom
reported. Based on our previous research [24], herein, we report
our recent results on Cu-catalyzed N-arylation of nitrogen-
containing heterocycles with aryl iodides and bromides under
mild conditions by using P,O bidentate derivatives as ligands.
frequently utilized by chemical, pharmaceutical, and materials
industries [1]. Thus, the development of correspondingly
convenient and efficient synthetic methods using these com-
pounds has attracted considerable attention. In the successful C–
N coupling methods, palladium [2], nickel [3] and copper [4]
catalysts, have been employed in the coupling of nucleophilic
aromatic substituents with aryl halides. The lower cost of
copper-based catalytic systems makes them particularly attrac-
tive for large-scale industrial applications, but requires synthetic
chemists to devise milder synthetic methods. The development
of new ligand structures for copper-catalyzed, cross-coupling
protocols also constitutes an area of considerable interest.
Recently, a series of novel mono- and bidentate ligands for Cu-
based C–N coupling were discovered, such as organic phosphane
ligands [5,6], N,N-bidentate ligands [7,8], O,O-bidentate ligands
[
9–14], and N,O-bidentate ligands [15–18]. In spite of the
significant recent progress, it is still necessary to search for more
efficient, air-stable and cheaper ligands, or metal-complexes, to
facilitate these coupling reactions under relatively milder
conditions.
2. Experimental
2.1. Materials and instruments
*
Corresponding author.
All reactions were carried out in air under magnetic stirring
conditions unless otherwise noted. H NMR spectral data were
1
E-mail address: liuping1979112@aliyun.com (P. Liu).
1
001-8417/$ – see front matter ß 2014 Ping Liu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
http://dx.doi.org/10.1016/j.cclet.2014.01.042
Please cite this article in press as: Y.-S. Liu, et al., 3-(Diphenylphosphino)propanoic acid: An efficient ligand for the Cu-catalyzed N-
arylation of imidazoles and 1H-pyrazole with aryl halides, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.01.042

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Table 1
a
Optimization of the reaction conditions.
N
I
[
Cu]/Ligand
N
HN
N
base, solvent
temp, time
Me
Me
Fig. 1. Structures of ligands 1 and 2.
3a
4a
5a
b
Entry
[Cu] (mol%)
Ligand (mol%)
Base
Solvent
Yield (%)
recorded on a Bruker DPX-400 spectrometers using TMS as internal
standard and CDCl or DMSO-d as solvent. EI-Mass spectra were
measured on a LC/Q-TOF MS (Micromass, England). All other
reagents were of analytical grade quality and commercially
obtained.
1
2
3
4
5
6
7
8
9
0
1
Cu(OAc) /2
1/4
NaOH
NaOH
NaOH
NaOH
NaOH
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
Toluene
DMF
20
41
66
52
33
0
2
Cu(OAc)
CuCl/2
2
/2
2/4
3
6
2/4
2
Cu O/2
2/4
CuI/2
2/4
CuCl/2
CuCl/2
CuCl/2
CuCl/2
CuCl/6
CuCl/8
CuCl/8
CuCl/8
CuCl/8
2/4
2
Na CO
3
2/4
Cs
2
CO
PO
NEt
3
38
15
0
2/4
K
3
4
2.2. General procedure for N-arylation of imidazoles and 1H-pyrazole
2/4
3
1
1
2/12
2/16
2/16
2/16
2/16
NaOH
NaOH
NaOH
NaOH
NaOH
87
97
0
(2-(Diphenylphosphino)acetic acid) L1 and (3-(diphenylpho-
sphino)propanoic acid) L2 (Fig. 1) were synthesized by the
literature methods [25].
12
13
13
0
14
1,4-dioxane
Procedure for N-arylation of imidazoles: CuCl (0.04 mmol), L2
a
(
0.08 mmol), aryl idione or bromide (0.5 mmol), imidazole or 1H-
benzo[d]imidazole (0.75 mmol), NaOH (1 mmol), and DMSO
1 mL) was added to a 5 mL tube, then sealed. The mixture was
stirred at 100 8C for certain time. After cooling to room
temperature, the mixture was quenched with 10 mL H O and
extracted with EtOAc (3 ꢀ 20 mL). The combined EtOAc extracts
were dried with anhydrous Na SO and filtrated and the solvent
Reaction conditions: 4-ioidotoluene (0.5 mmol), imidazole (1.0 mmol), base
(
1.0 mmol), and solvent (1 mL), 12 h, 100 8C.
b
Isolated yields.
(
2
combination of CuCl (8 mol%)/L2 (16 mol%), NaOH (2 equiv.) at
100 8C for 12 h in DMSO was chosen as the optimal conditions for N-
arylation of imidazole with 4-iodotoluene.
2
4
was removed under reduced pressure. The residue was purified by
flash column chromatography on silica gel with PE/EtOAc (from
The role of the CuCl/L2 system for general N-arylation of
imidazoles with various aryl halides was further evaluated and
summarized in Table 2. In general, most of aryl iodides reacted
with imidazole smoothly and the desired products were obtained
with moderate to excellent yields. Iodobenzene, as a substrate,
reacted with imidazole with only 62% yield (Table 2, entry 1),
but 1-chloro-4-iodobenzene, 1-fluoro-4-iodobenzene and 4-iodo-
2
:1 (v/v) to pure EtOAc) as the eluent to afford the desired
products.
Procedure for N-arylation of 1H-pyrazole: Cu(OAc)
0.03 mmol), L2 (0.06 mmol), aryl idione or bromide (0.5 mmol),
2
(
1
H-pyrazole (0.75 mmol), NaOH (1 mmol), and 1,4-dioxane (1 mL)
0
was added into a 5 mL tube, then sealed. The mixture was stirred at
00 8C for certain time. After cooling to room temperature, the
mixture was quenched with 10 mL H O and extracted with EtOAc
3 ꢀ 20 mL). The combined EtOAc extracts were dried with
anhydrous Na SO and filtrated and the solvent was removed
1,1 -biphenyl led to the N-arylated products with yields of 90–98%
1
(Table 2, entries 5–7). Furthermore, the catalytic system could
tolerate a variety of functional groups, including the nitro,
and ether groups (Table 2, entries 2, 4, and 8). When
2
(
2
4
under reduced pressure. The residue was purified by flash column
chromatography on silica gel with PE/EtOAc, as the eluent, to afford
the desired products.
Table 2
a
N-arylation of imidazoles with aryl halides catalyazed by CuCl/L2.
R
H
X
3
. Results and discussion
N
CuCl/L2
R
+
N
N
DMSO, NaOH
100°C, 12 h
N
3.1. Copper-catalyzed N-arylation reactions of imidazoles
4
4
a: imidazole;
b: 1H-benzo[d]imidazole
3
5
To optimize the reaction conditions, a series of reactionsbetween
4
-iodotoluene (3a) and imidazole (4a) were performed in the
presence of base and solvent to evaluate the roles of various ligands
and copper sources for the N-arylation process. As shown in Table 1,
among the explored different ligands and copper sources, L2
exhibited the highest catalytic activity with 41% yield (Table 1,
entries 1 and 2). The comparison of different copper sources
indicated that CuCl was superior to other sources, including
b
Entry
R, X (3)
Het-NH
Product
Yield (%)
1
2
3
4
5
6
7
8
9
H, I (3b)
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4a
4b
4b
4b
5b
5c
5d
5e
5f
62
94
20
77
93
98
90
77
78
92
61
94
70
87
4-OEt, I (3c)
4-COMe, I (3d)
2
4-NO , I (3e)
4-Ph, I (3f)
4-Cl, I (3g)
4-F, I (3h)
5g
5h
5i
Cu(OAc)
results of bases suggested that NaOH was the best (Table 1, entries
–9) and that 66% yield was achieved. The amount of Cu resource/L2
2 2
, Cu O, and CuI (Table 1, entries 3–5). The screening
3-OMe, I (3i)
2-Me, I (3j)
2-OMe, I (3k)
6
5j
10
11
12
13
5k
5l
was another important factor of the reaction investigated. When the
amount of Cu resource/L2 was increased from 2 mol%/8 mol% to
2-NH
4-NO
2
, I (3l)
, I (3e)
2
5m
5n
5o
4
9
mol%/16 mol%, the isolated yield of the product (5a) increased to
7% (Table 1, entries 10 and 11). Solvent was another important
4-Ph, I (3f)
4-Cl, I (3g)
14
factor in the catalysis. It was confirmed that DMSO was much better
than DMF. Meanwhile, and both toluene and 1,4-dioxane were not
suitable for use as reaction solvents (Table 1, entries 12–14). The
a
Reaction conditions: aryl halides (0.5 mmol), imidazoles (1.0 mmol), CuCl
(
8 mol%), L2 (16 mol%), NaOH (1.0 mmol), DMSO (1 mL), 100 8C, reaction time 24 h.
b
Isolated yields.
Please cite this article in press as: Y.-S. Liu, et al., 3-(Diphenylphosphino)propanoic acid: An efficient ligand for the Cu-catalyzed N-
arylation of imidazoles and 1H-pyrazole with aryl halides, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.01.042

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Y.-S. Liu et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
3
Table 3
1
-(4-iodophenyl)ethanone was used as the coupling partner, the
a
Optimization of the reaction conditions.
yield dropped to 20% (Table 2, entry 3). Notably, the sterically
demanding ortho substituents, such as 1-iodo-2-methylbenzene,
I
[
Cu]/Ligand
N
1
-iodo-2-methoxybenzene, and 2-iodoaniline, did not hamper the
N
HN
base, solvent
temp, time
N
N-arylation reactions and gave the coupling products with 61–92%
yields (Table 2, entries 9–11). In order to expand the scope of this
methodology, this new catalytic system was applied in the reaction
of imidazole derivatives. To our delight, aryl iodides reacted with
the 1H-benzo[d]imidazole and the corresponding products were
obtained with moderate to excellent yields under the optimized
reaction conditions. For example, 1-chloro-4-iodobenzene, and 1-
iodo-4-nitrobenzene afforded the corresponding products with
Me
Me
3a
6a
7a
b
Entry
[Cu]/(mol%)
CuCl/4
L2 (mol%)
Base
Solvent
Yield (%)
1
2
8
8
NaOH
NaOH
NaOH
NaOH
DMSO
19
16
22
49
21
20
28
19
13
60
72
79
76
82
91
Cu
2
O/4
DMSO
3
CuI/4
8
DMSO
4
Cu(OAc) /4
2
8
DMSO
8
7–94% yields (Table 2, entries 12 and 14). When the substrate, 4-
5
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
Cu(OAc)
2
2
2
2
2
2
2
2
2
2
/4
/4
/4
/4
/4
/4
/4
/8
/6
/6
8
Na
2
CO
3
DMSO
0
6
8
3
K PO
4
DMSO
iodo-1,1 -biphenyl, reacted with 1H-benzo[d]imidazole, the ary-
lated product with 70% yield was produced (Table 2, entry 13).
7
8
Et
3
N
DMSO
8
8
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
NaOH
DMF
9
8
Toluene
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
3.2. Copper-catalyzed N-arylation reactions of 1H-pyrazole
10
8
1
1
1
12
16
12
12
12
2
c
Then, we expanded the scope of the substrates to 1H-pyrazole,
1
3
but the above-mentioned catalytic system was not suitable for N-
arylation reaction of the pyrazole and required further optimiza-
tion of the N-arylation conditions. Subsequently, we selected the
d
1
4
e
15
2
Cu(OAc) /6
a
Reaction conditions: 4-ioidotoluene (0.5 mmol), 1H-pyrazole (1.0 mmol), base
1.0 mmol), solvent (1 mL), 12 h, 100 8C.
1
H-pyrazole and 4-iodotoluene as the substrates to further
(
b
investigate the effects of other factors on the N-arylation,
including copper resources, bases, solvents, reaction time and
reaction temperature. Among the different, investigated copper
Isolated yields.
c
1
20 8C.
8 h.
4 h.
d
e
1
2
sources, Cu(OAc)
were less efficient. For example, the reaction with 4 mol%
Cu(OAc) afforded the coupling product with 49% yield at
00 8C after 12 h, while only 16%–22% yields were obtained for
the same reaction with CuCl, Cu O, and CuI (Table 3, entries 1–4).
Among the tested various bases, NaOH was still the most effective
Table 3, entries 4–7). Solvent was an important factor of the
2 2
is the most efficient, while CuCl, Cu O, and CuI
2
Table 4
1
a
2
N-arylation of 1H-pyrazole with aryl halides catalyazed by Cu(OAc) /L2.
2
X
(
Cu(OAc)
2
/L2
N
N
N
R
+
catalysis. When 1,4-dioxane was used as the prime solvent, 60%
yield was obtained. DMSO, DMF and toluene gave relatively low
yields (Table 3, entries 7–9). Meanwhile, the increasing amount of
N
H
1,4-dioxane
NaOH, 100 °C
R
3
6a
7
Cu(OAc)
Table 3, entries 11–13). Furthermore, when the reaction time was
extended to 24 h, the highest yield is up to 91% (Table 3, entry 15).
Finally, the combination of Cu(OAc) (6 mol%)/L2 (12 mol%),
NaOH (2 equiv.) at 100 8C for 24 h in 1,4-dioxane was chosen as
the optimal conditions for N-arylation of 1H-pyrazole with 4-
iodotoluene.
The scope of substrates was then investigated with this
catalytic system under the optimized reaction conditions. As
shown in Table 4, in general, most of aryl iodides reacted with 1H-
pyrazole smoothly and the desired products were produced with
moderate to excellent yields. Iodobenzene, as a substrate, reacted
readily with 1H-pyrazole and gave 83% yield (Table 2, entry 1), and
electronic effects seem to have no significant impact on the
coupling reactions. For example, aryl iodide with an electron-
donating group could be coupled with 1H-pyrazole to give
corresponding product with 84%–98% yield (Table 4, entries 2
and 9), and aryl iodides with electron-withdrawing groups,
including 1-chloro-4-iodobenzene, 1-fluoro-4-iodobenzene, 1-
bromo-4-iodobenzene, 1-iodo-4-nitrobenzene and 1-(4-iodophe-
nyl)ethanone also afforded the corresponding arylated products
2
/L2 and reaction temperature led to the increasing yields
(
b
Entry
R, X (3)
Product
Yield (%)
1
2
H, I (3b)
7b
7c
7d
7e
7f
83
84
60
89
90
82
67
89
98
40
54
74
54
71
51
2
4-OMe, I (3m)
4-COMe, I (3d)
3
4
2
4-NO , I (3e)
5
4-Ph, I (3f)
4-Cl, I (3g)
4-Br, I (3n)
4-F, I (3h)
6
7g
7h
7i
7
8
9
3-OMe, I (3i)
2-Me, I (3j)
2-OMe, I (3k)
7j
10
7k
7l
1
1
1
2
c
2-NH
4-Me, Br (3o)
4-NO , Br (3p)
2-OMe, Br (3q)
2
, I (3l)
7m
7n
7e
7o
13
c
c
14
2
15
a
Reaction conditions: aryl halide (0.5 mmol), 1H-pyrazole (1.0 mmol), Cu(OAc)
2
(6 mol%), L2 (12 mol%), NaOH (1.0 mmol), and 1,4-dioxane (1 mL), 100 8C, 24 h.
b
Isolated yields.
c
120 8C, 36 h.
with 60%–89% yields (Table 4, entries 3, 4 and 6–8). When 4-iodo-
the desired products in 51%–71% yields at 120 8C for 36 h (Table 4,
entries 13–15).
0
1
,1 -biphenyl was used as the coupling partner, the 90% yield was
obtained (Table 4, entry 5). Furthermore, the sterically demanding
ortho substituents, such as 1-iodo-2-methylbenzene, 1-iodo-2-
methoxybenzene, and 2-iodoaniline, did not hamper the arylation
reaction and 40%–74% yields were achieved (Table 4, entries 10–
4. Conclusion
In conclusion, L2 was proved to be an efficient ligand for not
only the CuCl-catalyzed N-arylation of imidazoles with aryl iodides
1
2). In addition, the reactions of aryl bromides, such as 1-bromo-4-
methylbenzene, 1-bromo-4-nitrobenzene, and 1-bromo-2-meth-
2
in DMSO, but also the Cu(OAc) -catalyzed N-arylation of 1H-
oxybenzene with 1H-pyrazole, were also successful and provided
pyrazole with aryl iodides and even aryl bromides in 1,4-dioxane.
Please cite this article in press as: Y.-S. Liu, et al., 3-(Diphenylphosphino)propanoic acid: An efficient ligand for the Cu-catalyzed N-
arylation of imidazoles and 1H-pyrazole with aryl halides, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.01.042

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Y.-S. Liu et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
[
[
12] F.Y. Kwong, S.L. Buchwald, Mild and efficient copper-catalyzed amination of aryl
The proposed catalytic method is characterized by a facile catalytic
system, mild reaction conditions, experimental simplicity, and
broad substrate scope. The reaction mechanism and the expansion
of the scope of the catalytic system are currently studied in our
laboratory.
bromides with primary alkylamines, Org. Lett. 5 (2003) 793–796.
13] (a) A. Shafir, S.L. Buchwald, Highly selective room temperature copper-catalyzed
C–N coupling reactions, J. Am. Chem. Soc. 128 (2006) 8742–8743;
(b) Z.X. Xi, F.H. Liu, Y.B. Zhou, W.Z. Chen, CuI/L (L = pyridine-functionalized 1,3-
diketones) catalyzed C–N coupling reactions of aryl halides with NH-containing
heterocycles, Tetrahedron 64 (2008) 4254–4259;
(c) X.H. Zhu, L. Su, L.Y. Huang, et al., A facile and efficient oxalyldihydrazide/
ketone-promoted copper-catalyzed amination of aryl halides in water, Eur. J. Org.
Chem. (2009) 635–642.
Acknowledgments
[
[
14] X. Lv, W.L. Bao, A b-keto ester as a novel, efficient, and versatile ligand for
copper(I)-catalyzed C–N, C–O, and C–S coupling reactions, J. Org. Chem. 72 (2007)
We gratefully acknowledge financial support of this work by
the National Basic Research Program of China (973 Program, No.
3863–3867.
15] (a) H.J. Cristau, P.P. Cellier, J.F. Spindler, M. Taillefer, Highly efficient and mild
copper-catalyzed N- and C-arylations with aryl bromides and iodides, Chem. Eur.
J. 10 (2004) 5607–5622;
2
012CB722603), the Program for Changjiang Scholars and
Innovative Research Team in University (No. IRT1161), the
National Natural Science Foundation of China (No. 21103114),
and the Doctor Foundation of Xinjiang Bingtuan (No. 2012BB010).
(b) Z.Q. Wu, Z.Q. Jiang, D. Wu, H.F. Xiang, X.G. Zhou, A simple and efficient
catalytic system for coupling aryl halides with aqueous ammonia in water, Eur. J.
Org. Chem. (2010) 1854–1857;
(
c) Z.Q. Wu, L. Zhou, Z.Q. Jiang, et al., Sulfonato–Cu(salen) complex catalyzed N-
arylation of aliphatic amines with aryl halides in water, Eur. J. Org. Chem. (2010)
971–4975;
References
4
[
1] N.R. Candeias, L.C. Branco, P.M. Gois, C.A.M. Afonso, A.F. Trindade, More sustain-
able approaches for the synthesis of N-based heterocycles, Chem. Rev. 109 (2009)
(d) Y. Wang, Z.Q. Wu, L.X. Wang, Z.K. Li, X.G. Zhou, A simple and efficient catalytic
system for N-arylation of imidazoles in water, Chem. Eur. J. 15 (2009) 8971–8974.
2
703–2802.
[16] (a) D.W. Ma, Q. Cai, H. Zhang, Mild method for Ullmann coupling reaction of
amines and aryl halides, Org. Lett. 5 (2003) 2453–2455;
[
2] J.F. Hartwig, Palladium-catalyzed amination of aryl halides and sulfonates, in: A.
Ricci (Ed.), Modern Amination Methods, Wiley-VCH, Weinheim, 2000, pp. 195–262.
3] (a) J.P. Wolfe, S.L. Buchwald, Nickel-catalyzed amination of aryl chlorides, J. Am.
Chem. Soc. 119 (1997) 6054–6058;
(
b) D.W. Ma, Q. Cai, L-Proline promoted Ullmann-type coupling reactions of aryl
iodides with indoles, pyrroles, imidazoles or pyrazoles, Synlett (2004) 128–130;
c) Q. Cai, H. Zhang, W. Zhu, Y.D. Zhang, D.W. Ma, Preparation of N-aryl com-
[
(
(
b) C. Desmarets, R. Schneider, Y. Fort, Nickel(0)/dihydroimidazol-2-ylidene
pounds by amino acid-promoted Ullmann-type coupling reactions, Synthesis
(2005) 496–499;
complex catalyzed coupling of aryl chlorides and amines, J. Org. Chem. 67
(d) H. Zhang, Q. Cai, D.W. Ma, Amino acid promoted CuI-catalyzed C–N bond
(2002) 3029–3036;
(
c) S. Tasler, B.H. Lipshutz, Nickel-on-charcoal-catalyzed aromatic aminations
formation between aryl halides and amines or N-containing heterocycles, J. Org.
Chem. 70 (2005) 5164–5173;
(e) X. Lv, Z.M. Wang, W.L. Bao, CuI catalyzed C–N bond forming reactions
and Kumada couplings: mechanistic and synthetic aspects, J. Org. Chem. 68
2003) 1190–1199.
(
[
[
4] (a) F. Monnier, M. Taillefer, Catalytic C–C, C–N and C–O Ullmann-type coupling
reactions, Angew. Chem. Int. Ed. 48 (2009) 6954–6971;
between aryl/heteroaryl bromides and imidazoles in [Bmim]BF
62 (2006) 4756–4761.
[17] (a) Z.K. Lu, R.J. Twieg, S.D. Huang, Copper-catalyzed amination of aromatic
halides with 2-n,n-dimethylaminoethanol as solvent, Tetrahedron Lett. 44
(2003) 6289–6292;
4
, Tetrahedron
(
b) M.G. Boswell, F.G. Yeung, C. Wolf, Copper-catalyzed C–N bond formation with
N-heterocycles and aryl halides, Synlett 23 (2012) 1240–1244;
c) Y.C. Teo, F.F. Yong, G.S. Lim, A manganese/copper bimetallic catalyst for C–N
coupling reactions under mild conditions in water, Tetrahedron Lett. 52 (2011)
171–7174.
(
(b) Z.K. Lu, R.J. Twieg, Copper-catalyzed aryl amination in aqueous media with 2-
7
dimethylaminoethanol ligand, Tetrahedron Lett. 46 (2005) 2997–3001.
[18] H.H. Rao, H. Fu, Y.Y. Jiang, Y.F. Zhao, Copper-catalyzed arylation of amines using
diphenyl pyrrolidine-2-phosphonate as the new ligand, J. Org. Chem. 70 (2005)
8107–8109.
5] (a) R.K. Gujadhur, D. Venkataraman, J.T. Kintigh, Formation of aryl-nitrogen
bonds using a soluble copper(I) catalyst, Tetrahedron Lett. 42 (2001) 4791–4793;
(b) R.K. Gujadhur, C.G. Bates, D. Venkataraman, Formation of aryl-nitrogen, aryl-
[
19] W. Keim, Vor- und Nachteile der homogene U¨ bergangs metallkatalyse, dargestellt
oxygen, and aryl-carbon bonds using well-defined copper(I)-based catalysts, Org.
Lett. 3 (2001) 4315–4317.
am SHOP–Prozeb, Chem. Ing. Tech. 56 (1984) 850–853.
[
6] M.H. Yang, F. Liu, An Ullmann coupling of aryl iodides and amines using an air-
stable diazaphospholane ligand, J. Org. Chem. 72 (2007) 8969–8971.
7] (a) A. Kiyomori, J.F. Marcoux, S.L. Buchwald, An efficient copper-catalyzed coupling
of aryl halides with imidazoles, Tetrahedron Lett. 40 (1999) 2657–2660;
[20] (a) A. Bader, E. Lindner, Coordination chemistry and catalysis with hemilabile
oxygen–phosphorus ligands, Coord. Chem. Rev. 108 (1991) 27–110;
(b) G.J.P. Britovsek, W. Keim, S. Mecking, D. Sainzb, T. Wagner, Hemilabile P,O-
ligands in palladium catalysed C–C linkages: codimerization of ethylene and
styrene and cooligomerization of ethylene and carbon monoxide, J. Chem. Soc.
Chem. Commun. (1993) 1632–1634.
[
(
b) L.B. Liu, M. Frohn, N. Xi, et al., A soluble base for the copper-catalyzed imidazole
N-arylations with aryl halides, J. Org. Chem. 70 (2005) 10135–10138;
c) A.A. Kelkar, N.M. Patil, R.V. Chaudhari, Copper-catalyzed amination of aryl
halides: single-step synthesis of triarylamines, Tetrahedron Lett. 43 (2002)
143–7146;
d) Y.H. Liu, C. Chen, L.M. Yang, Diazabutadiene: a simple and efficient ligand for
copper-catalyzed N-arylation of aromatic amines, Tetrahedron Lett. 47 (2006)
275–9278.
(
[21] (a) X. Du, X.J. Feng, Y. Liu, R. He, M. Bao, Suzuki reaction of bromoallenes with
arylboronic acids using an air-stable palladium complex Pd(Ph
precatalyst, Chin. Chem. Lett. 21 (2010) 641–644;
2 2 2 2
PCH CO ) as a
7
(
(b) L. Zhou, Q.Q. Miao, R. He, X.J. Feng, M. Bao, Ni-catalyzed cross-coupling
reaction of aryl chlorides with arylboronic acids in IPA without using a reducing
reagent, Tetrahedron Lett. 48 (2007) 7899–7902.
9
[
8] (a) J.C. Antilla, A. Klapars, S.L. Buchwald, The copper-catalyzed N-arylation of
indoles, J. Am. Chem. Soc. 124 (2002) 11684–11688;
[22] (a) M.P. Guo, F.F. Jian, R. He, Efficient synthesis of fluorinated biphenyl derivatives
via Pd-catalyzed Suzuki coupling reactions in aqueous solvents at room temper-
ature, J. Fluorine Chem. 27 (2006) 177–181;
(
b) A. Klapars, X.H. Huang, S.L. Buchwald, A general and efficient copper catalyst
for the amidation of aryl halides, J. Am. Chem. Soc. 124 (2002) 7421–7428;
c) B. Mallesham, B.M. Rajesh, P.R. Reddy, D. Srinivas, S. Trehan, Highly efficient
(b) M.P. Guo, F.F. Jian, R. He, Cross coupling reactions catalyzed by P,O chelate
(
palladium complexes at room temperature, Tetrahedron Lett. 46 (2005) 9017–
9020.
CuI-catalyzed coupling of aryl bromides with oxazolidinones using Buchwald’s
protocol: a short route to Linezolid and Toloxatone, Org. Lett. 5 (2003) 963–965;
[23] E. Ullah, J. McNulty, A. Robertson, A novel P,O-type phosphorinane ligand for the
Suzuki–Miyaura cross-coupling of aryl chlorides, Tetrahedron Lett. 50 (2009)
(d) P.S. Wang, C.K. Liang, M.K. Leung, An improved Ullmann–Ukita–Buchwald–Li
5
599–5601.
conditions for CuI-catalyzed coupling reaction of 2-pyridones with aryl halides,
Tetrahedron 61 (2005) 2931–2939;
[24] (a) F.T. Wu, P. Liu, X.W. Ma, J.W. Xie, B. Dai, Tetrazole-1-acetic acid as a ligand for
copper-catalyzed N-arylation of imidazoles with aryl iodides under mild condi-
tions, Chin. J. Chem. 24 (2013) 893–896;
(
e) E. Alcalde, I. Dinares, S. Rodr ı´ guez, C.G. de Miguel, Synthetic approaches to
sterically hindered n-arylimidazoles through copper-catalyzed coupling reac-
tions, Eur. J. Org. Chem. (2005) 1637–1643;
(b) Y.L. Jiao, N.N. Yan, J.W. Xie, et al., A simple and efficient copper(II) complex as a
catalyst for N-arylation of imidazoles, Chin. J. Chem. 31 (2013) 267–270;
(c) Y. Liu, Q. Zhang, X.W. Ma, et al., Salen-Cu(II) complex catalyzed N-arylation of
imidazoles under mild conditions, Inter. J. Org. Chem. 3 (2013) 185–189;
(d) Y. Liu, W. Liu, Q. Zhang, et al., Salen-Cu(II) complex catalyzed N-arylation of
pyrazole under mild conditions, J. Chem. Res. (2013) 636–637.
(
f) P.E. Maligres, S.W. Krska, P.G. Dormer, A soluble copper(I) source and stable
salts of volatile ligands for copper-catalyzed C–X couplings, J. Org. Chem. 77
2012) 7646–7651.
(
[
9] F.Y. Kwong, A. Klapars, S.L. Buchwald, Copper-catalyzed coupling of alkylamines
and aryl iodides: an efficient system even in an air atmosphere, Org. Lett. 4 (2002)
[25] (a) K. Issleib, G. Thomas, Basizita
yalkylphosphinen und deren derivaten, Z. Anorg. Allg. Chem. 330 (1964) 295–
08;
(b) K. Issleib, G. Thomas, Alkali-Phosphorverbindungen und ihr reaktives Ver-
¨
ts, IR und NMR untersuchungen an carbox-
5
81–584.
[
10] Y.J. Chen, H.H. Chen, 1,1,1-Tris(hydroxymethyl)ethane as a new, efficient, and
versatile tripod ligand for copper-catalyzed cross-coupling reactions of aryl
iodides with amides, thiols, and phenols, Org. Lett. 8 (2006) 5609–5612.
11] D.S. Jiang, H. Fu, Y.Y. Jiang, Y.F. Zhao, CuBr/rac-BINOL-catalyzed N-arylations of
aliphatic amines at room temperature, J. Org. Chem. 72 (2007) 672–674.
3
halten, V. Darstellung von Carboxyphosphinen R
(1960) 803–808.
2 2 n 2
P-[CH ] -CO H, Chem. Ber. 93
[
Please cite this article in press as: Y.-S. Liu, et al., 3-(Diphenylphosphino)propanoic acid: An efficient ligand for the Cu-catalyzed N-
arylation of imidazoles and 1H-pyrazole with aryl halides, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.01.042